13.8 a/f ratio, why? - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 09-09-2007, 11:36 PM   #21
Ben
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Rich--WTF are you talking about? What do you think my post, "just get a fuel pump." (number 8 in the thread) meant?

to tune the BEGi FMU, you start at WG pressure. tune the overall pressure first and the rising rate second. then add the MBC and increase boost until you're out of fuel, then go back down a smidge. that's it, and that's all. no fuel pressure gauge required. it would take longer to install a fuel pressure gauge than it would to actually tune the damn fmu. i think the last time I had to do it on my car, it took me about 10 minutes to dial in--and I nailed it pretty good.

now, say you get your fuel dialed in, and 6 months later you're running lean up top. that's when you should employ a fuel pressure gauge as a diagnostic tool.

now I don't see a begi t28 making 7-8 psi post intercooler w/o help of a mbc. anything's possible, but I doubt corky's shipping the turbos out with a 10 psi wg. so the op needs to pull his mbc. his stock pump has no chance of supplying enough fuel in a pressure based system.
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Old 09-10-2007, 04:07 PM   #22
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Quote:
Originally Posted by Ben View Post
phil: that graph is useless w/o any telemetry. next time you go to the dyno, pay the extra $10-15 to capture a/f, intake temp, and mani pressure. that way you get the whole picture. search for the JAW wideband. it's dirt cheap and will help you tune properly.
The JAW setup looks interesting.

http://www.14point7.com/JAW/JAW.htm

So you can buy the Bosch LSU 4 Wideband O2 sensor for around $50? Is that right? And it will work with the stock computer? Sorry if that is a dumb question.

http://wbo2.com/lsu/
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Old 09-10-2007, 04:11 PM   #23
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what ben says makes sense. screw knowing the acutal fuel pressure if the AFR looks good.
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Old 09-10-2007, 04:23 PM   #24
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Is it possible to tune the car with one of those ricer pepboys off the shelf a/f meters? Would I be able to get my a/f ratio even close with one of them, or are they a total waste of time?
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Old 09-10-2007, 04:30 PM   #25
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no
no
yes

*assuming 'ricer ... a/f meter' means narrow band
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Old 09-10-2007, 04:33 PM   #26
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thats what I thought, Thanx
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